The first reception of the Timaeus in the sciences and natural philosophy we find in Aristotle, especially in his Physics and in his De Caelo(exhibit number 11 and 12). For Aristotle the Timaeus was especially important, among other reasons, because, as Aristotle states in the Physics passage shown, Plato was the only one who had dealt with the problem of space/place in a scientific way before. A very special kind of reception is the text Peri psychas kosmô kai physios, which allegedly shows some of the pre- rather than of the afterlife of the Timaeus. Written in the first century AD it was passed off as a pre-Platonic text by the Pythagorean Timaeus of Locri, on which Plato’s Timaeus was supposed to have drawn. The Neoplatonists were the first to accept it as an authentic document; but others did as well, as can be seen from the fact that Henricus Stephanus’ edition (exhibit number 5) has this text printed in between Plato’s Timaeus and Critias; this is the reason why the Stephanus pagination of the Critias is not immediately continuous with that of the Timaeus.

The Timaeus drew a strong reception also during the Middle Ages. One essential reason for this was its obvious compatibility in many respects with the book of Genesis. The Timaeus was paired up with Genesis probably already as early as the 2nd century BC by Aristobulus, an intertwining anchored by Philo of Alexandria who focused on the parallels between Platonic cosmogony and the account of creation in the first book of Moses13.

At times the differences between these two accounts of creation were stressed more than the similarities14, notably the difference between god as the single cause for the creation in Genesis and the three principles necessary for the creation in the Timaeus, the demiurge, the receptacle and the model (Forms). Especially Ambrose in his exegesis of Genesis in the 4th AD century pointed these differences out as “errors” of Plato. Ambrose thought these “errors” had already been refuted by Moses since Genesis starts out with “in the beginning god created heaven and earth”, thus, according to Ambrose, implying that everything, even the independent first principles of the Timaeus, is in fact created by god.

However, Ambrose’s student Saint Augustine15and later on also Boethius16 focused on the similarities again — Augustine explicitly mentions as a point of agreement the same beginning passage from Genesis used by Ambrosius to point out the incompatibility of the Timaeus and Genesis17 — and thus prepared the way for the Timaeus into the Middle Ages. The 12th century was especially crucial in the reception of Plato: the first half of the century marked the climax of his reception in the Middle Ages, as can be seen in particular with the School of Chartres where Bernard of Chartres’ and William of Conches’ Glosae super Platonem were produced. In the second half, however, the study of Plato diminished and became either insignificant (thus in the translation movement of the 12th century Plato’s oeuvre beyond the Timaeus did not raise much interest) or suspect (as can be seen in the trial of Abelard where the preoccupation with Plato was regarded as a possible seduction away from Christ).18 While Aristotle gained more and more influence with his newly translated works in natural philosophy as well as metaphysics and ethics in the later part of the 12th century in addition to his already translated logical works, Plato and his Timaeus were increasingly marginalised. Overcoming this marginalisation and rediscovering Plato and his Timaeus as an important philosophical document is an essential feature of the Renaissance. And it is this new evaluation of Plato’s Timaeus which provided us with the core items of this exhibition.

In the Renaissance, the Timaeus is again read as being very close to the conception of Genesis; so e.g. Ficino identified Plato’s demiurge with the Christian creator god and the Forms with god’s own mind19; in the Ficino edition of Plato from 1556 Plato (in Neoplatonic tradition) is even addressed as being divine: “Omnia Divini Platonis Opera” (exhibit number 10). And Kepler in his Harmonice Mundi calls the Timaeus “a kind of commentary on the first chapter of Genesis, or the first book of Moses, converting it to the Pythagorean philosophy” (exhibit number 14). Some 200 years later Schelling actually proposed that the Timaeus was not written by Plato but by a late Christian author.20

However, it is not only this new emphasis on its compatibility with Genesis that made the Timaeus a significant book for the Renaissance. It is also its combination of mathematics and physics that made it attractive for the newly reawakened sciences. Accordingly, Johannes Kepler uses the Timaeus to justify his own merging of mathematics and physics in his astronomy21which is a central point in his Astronomia nova. Nonetheless, Kepler did not simply take the Platonic text as an authority, as was done in the commentators’ tradition. Rather he considered the Timaeus as a resource to draw on for his cosmological questions. And the question which inspired Kepler to write his Mysterium Cosmographicum was how to give a rational account of the distances between the planets which one could attempt to calculate only once the sun was placed in the middle of the universe. The answer Kepler took from the Timaeus was the five Platonic solids (exhibit number 15) and the relative distances between them which are achieved if they are nested in each other (exhibit number 13); we show the second edition which was expanded with notes by Kepler). The number of the solids (given Euclid’s proof in Elements book XIII, Prop. 18 that there can only be five such solids) explains why there must be exactly six planets (the five solids are needed to separate six spheres), and the geometry of their nesting gives us the distances – this enabled Kepler to retain his belief that god did everything for a cause, so also the arrangement of the universe, and to give a scientific model for the empirical data.

In this way, Kepler as one of the early defenders of the Copernican world view tried originally to give Plato a place in this new system which obviously contradicts Plato’s (and Ptolemy’s) geocentric view. One other aspect of Platonic astronomy Kepler had originally taken up is Plato’s insistence on uniform circular motion as being the one motion most akin to reason (Timaeus 34a) and hence the only one adequate for the motions of the heavenly bodies. Overcoming this Platonic idea by building on Tycho Brahe’s data led to Kepler’s famous first law that the planets revolve around the sun not in circular but in elliptical orbits having the sun as one focus (published in his Astronomia nova in 1609). The discovery of this first law helped to strengthen the heliocentric view of Copernicus who himself had followed Plato’s demand for uniform circular motion22for the heavenly bodies in an even stricter way than Ptolemy did centuries ago in his Almagest.

The edition of the Almagest on display (exhibit number 18) is the version with which Copernicus was introduced to Ptolemy. It is a précis done by the Austrian astronomer Georg von Peuerbach and the German astronomer Johannes Müller von Königsberg (know as Regiomontanus). Included in Regiomontanus’ notes on the 12th book of the Almagest is his demonstration of an alternative to Ptolemy’s model of Mercury and Venus’ orbits relative to the sun; this demonstration is believed to have actually assisted Copernicus to postulate that the planets move around the sun.23

While Ptolemy could not strictly adhere to Plato’s fundamental claim of the uniformity of heavenly motion, he certainly observed Plato’s dictum that astronomers should try to find a reasonable hypothesis which would “save the phenomena”, salvare apparentia24 (i.e. a rational account should be given of all the phenomena that can be observed) not only for the motions of the planets25, but also for the stars. His placement of the stars within constellations seems to be based on star maps, or perhaps even on a celestial globe (the Farnese globe at Naples surviving from ancient times is generally believed to be a Roman copy of an earlier Greek one, cf. also the celestial globe in the exhibition, exhibit number 16). This tradition of star maps building on Ptolemy is taken up again in the Renaissance, the first printed one is made by Albrecht Dürer, numbering the stars according to Ptolemy’s list. The first person to produce what is considered the first star atlas was Johannes Bayer in his Uranometria from 1603 (exhibit number 17). He extended the 48 constellations tabulated by Ptolemy by 12 new constellations of the Southern hemisphere found by the first Dutch expedition to the East Indies and improved the accuracy of the old constellations with the help of Tycho Brahe’s data.

17 Augustine, City of God, book VIII, chapter xi. For Augustine, the Timaeus also rightly points out that god is neither created nor changeable and in general, Plato and the Platonists are the philosophers who come nearest to Christianity.

18 Ricklin, op.cit.

19 M. Allen, op. cit., p. 239. Ficino thus took up a reading common since Philo.

24 This is handed down to us by Simplicius and refered to as a guiding principle by Copernicus in his De hypothesibus motuum caelestium a se constitutis commentariolus, cf. Klibansky, op. cit. p. 26.

25 Like in the Timaeus Ptolemy explains seemingly irrational motions of the planets by the combination of different circular motions, cf. e.g. Almagest, book I.8, even if for Ptolemy they are only uniform around centres other than the centres of the circles of their motion.